Wow they look great, alot different to our "Bungee" leads. I have found them very usuful especially when we are out at Flyball comps and the dogs are excited and bouncing around, saves my arms alot of stress.

I don't really understand how it works. Is it just when the dog pulls the leash extends?

they seem to work like a bungy ??
this is what my dogfancy says about them
"made with latex modeled after the fitness industry, alleviates stress on dog and owner during walks. The leash adjusts to resistance when you dog pulls, shifting the burden from you to the leash itself. The harder your dog pulls, the more responsive the leash is, gently correcting wandering or impatient dogs. The leash also comes in double models to walk more then one dog at a time." I am not entirely sure that helped or not but the website might explain it better?

they seem to work like a bungy ??
this is what my dogfancy says about them
"made with latex modeled after the fitness industry, alleviates stress on dog and owner during walks. The leash adjusts to resistance when you dog pulls, shifting the burden from you to the leash itself. The harder your dog pulls, the more responsive the leash is, gently correcting wandering or impatient dogs. The leash also comes in double models to walk more then one dog at a time." I am not entirely sure that helped or not but the website might explain it better?